1. Field of the Invention
This invention relates generally to implementation of a short messaging service (SMS) over an SGs interface.
2. Background of Related Art
Long Term Evolution (LTE) 4G wireless broadband technology is an all-Internet Protocol (IP) based technology that supports packet based services only (i.e., it supports services solely over the Internet).
While a majority of commercial service providers can be expected to adopt an all-Internet Protocol (IP) based technology (e.g. long term evolution) at some time in the near future, a great deal of today's mobile services are still circuit-switched (CS) (i.e. supported by a legacy circuit-switched (CS) network). To enable user equipment (UE) serviced by a Long Term Evolution (LTE) technology (i.e. all Internet Protocol (IP) based technology) to provide circuit-switched (CS) services (voice, SMS, location, etc.), the mobile user equipment (UE) falls back to the circuit-switched (CS) domain.
FIG. 8 depicts a conventional architecture interfacing an IP-based Long Term Evolution (LTE) network with a circuit-switched (CS) 3G network. In such architecture, there is no CS fallback for SMS services over the SGs link.
As portrayed in FIG. 8, an SGs interface 114 interconnects a mobile management entity (MME) 116 on a Long Term Evolution (LTE) network (e.g., Evolved Packet Core (EPC) network) 104 with a gateway-mobile switching center (MSC) server 900 on a circuit-switched (CS) network (e.g., 2G/3G core network) 100 to permit messaging between the two entities.
But to provide SMS services to the UE 102, the 3G core network 100 must be updated to support the new SGs interface. To do so, the MME 116 must perform complex HPLMN routing to the CS domain, and the MME 116 must manage SCTP associations to every MSC server 120 within the 3G network 100.
FIG. 9 depicts a conventional roaming architecture for providing short message service (SMS) over an SGs interface, causing circuit-switched (CS) fallback messaging 106.
In particular, a mobile device 102 can only fallback to 3G in the case where evolved UMTS terrestrial radio access network (E-UTRAN) coverage (e.g., LTE) 108, is overlapped by either a GSM EDGE Radio Access Network (GERAN) 110 or a 3G Universal Terrestrial Radio Access Network (UTRAN) 112.
The mobile management entity (MME) 116 in the Long Term Evolution (LTE) network 104 is interconnected with each MSC Server 120 in the circuit-switched (CS) network (e.g. 3G core network) 100 via an SGs interface 114, to enable SMS messages to be routed between the two domains.
When the mobile switching center (MSC) server 120 on the circuit-switched (CS) network (i.e. 3G core network) 100 receives an SMS message addressed to the user equipment (UE) 102 serviced by a Long Term Evolution (LTE) network 104, the mobile switching center (MSC) server 120 forwards the SMS message over the SGs interface 114 to a mobile management entity (MME) 116 on the Long Term Evolution (LTE) network 104. The mobile management entity (MME) 116 then forwards the SMS message to the intended user equipment (UE) 102.
Similarly, when the user equipment (UE) 102 serviced by the Long Term Evolution (LTE) network 104 initiates an SMS message, the originating user equipment (UE) 102 passes the SMS message to a serving mobile management entity (MME) 116 on the Long Term Evolution (LTE) network 104, which subsequently forwards the SMS message over the SGs interface 114 to the mobile switching center (MSC) server 120 on the circuit-switched (CS) network 100. The SMS message is then routed to an intended message recipient.
FIG. 10 depicts a conventional SGs interface protocol stack.
As depicted in FIG. 10, an SGs application part (AP) protocol 800 over a Stream Control Transmission Protocol (SCTP) 810 is used to route messages over a conventional SGs interface 114.
The present inventors have recognized, and appreciated, that fallback signaling to 3G can cause considerable service delays.